Using a non-human primate model of normal aging, this investigation will explore the role of adult cell genesis in the hippocampus and surrounding areas of the primate brain. Bromodeoxyuridine (BrdU, a marker of cell proliferation) will be injected into both young and old rhesus monkeys (Macaca mulatta). After injection of BrdU, a subset of monkeys will be given a behavioral task to induce neurogenesis. Post-mortem analysis of brain tissue using immunohistochemistry, stereology, and confocal microscopy, will identify newly created neurons, astrocytes, and oligodendrocytes. This study will analyze two sets of experimental data. 1) Differentiation of newly created cells under basal conditions will be examined in young and old animals. Preliminary results suggest that there are changes in adult cell genesis with age; the details of these changes will be explored. 2) Learning has been shown to increase adult neurogenesis in the hippocampus. This plasticity will be compared in young and old animals that received post-BrdU behavioral testing. It has been established that cognitive decline occurs with age. This proposed investigation will determine if there are changes in adult cell genesis that could be important in the neurobiological basis of age-related cognitive decline. [unreadable] [unreadable]